Arrangement for causing an indication upon the interruption of a load circuit



July 27, 1965 s. HELLMAN 3,197,674 ARRANGEMENT FOR C ING' AN INDICATION UPON" THE I INT ERRU ION OF A LOAD CIRCUIT F d June 23, 1961 FIG. 5 MENTOR STEN G. HELLMAN BY Jmq QQQQ) Day/ 1 ATTORNE United States Patent M 3,197,674 ARRANGEMENT FOR CAUSING AN INDICATION UPON THE INTERRUPTION OF A LOAD CIR- CUIT Sten Gustaf Hellman, Lidingo, Sweden, assignor to AGA Aktiebolag, Lidingo, Sweden, a corporation of Sweden Filed June 23, 1961, Ser. No. 119,097 Claims priority, application Sweden, July 11, 1960, 6,785/60 4 Claims. (Cl. 315-88) The present invention relates to an arrangement for causing an indication by means of a relay, which is actuated upon the interruption of a load circuit which is connected to a voltage source. The load will be assumed in the following to consist of a lamp. The indication to be caused upon interruption of the lamp circuit may consist in the insertion of a stand-by load, such as a stand-by lamp, or in the actuation of an indicator located at a control site. In the following description of the invention, it will be assumed that a stand-by lamp is to be inserted upon an interruption in the circuit of the regular lamp. According to the invention, the relay winding is adapted, in normal operation, to have current flowing through it from an impedance in parallel with the load as long as a switch which is in series with the load is closed, and to have current flow through it from an impedance in parallel with the switch when the latter is non-conductive, the indication being arranged to be caused when the current through the relay winding drops to zero.

The invention will be described in the following with reference to the attached drawing showing a number of different embodiments thereof. The FIG. I arrangement can be connected to a voltage source for D.C. or A.C. with the aid of terminals 1 and 2. The normally operative lamp 3 is in series with a switch 4 and a twoway contact of a relay 6 connected to the voltage source. The switch 4 is assumed to be controlled by a control member 5 in such a way that the switch 4 is closed intermittently and preferably periodically. If the lamp 3 is the light-source of a beacon, it is possible to obtain a desired signal character by suitably constructing the control member 5. The two-way contact in the connection between the lamp 3 and the switch 4 responds to the relay 6, the switch 4 being connected to the movable contact arm and the lamp 3 to the make-contact. Furthermore, the break-contact of the switch is conected to a stand-by lamp 7. The relay winding is connected between the make-contact and the junction point of two impedances 3 and 9, which are conected in series between the terminals 1 and 2. In the A.C. case, the impedances can be of an arbitrary kind. In FIG. 1, they are assumed to be resistors.

The FIG. 1 arrangement operates as follows: Upon the connection of a voltage source to the contacts 1 and 2, a current passes through the lamp 3, the relay winding and the impedance 9, causing the relay to respond and connect the lamp 3 in series with the switch 4. As long as the lamp 3 is in order, a current flows through the lamp 3, the relay Winding and the impedance 9, when the switch 4 is non-conductive, and when the switch is conductive, a current flows through the impedance 8, the relay winding and the switch 4. The relay 6, therefore, will be constantly energized, as long as the lamp is in order. If a break occurs in the lamp 3, the current through the relay winding is interrupted when the switch 4- becomes non-conductive, the relay 6 is de-energized and connects the stand-by lamp 7 in circuit. As was mentioned above, some other type of indication may be caused at the same time, for instance with the aid of additional contacts on the relay 6.

The FIG. 1 arrangement differs from the other embodi- 3,197,674 Patented July 27, 1965 ments to be described in the following in that it can be used for D.C. as well as for A.C. However, it has a drawback consisting in that the arrangement draws current even after an interruption has occurred in the normally operative lamp 3. In this respect, the other embodiments described are preferable.

In the FIG. 2 arrangement, which is adapted for connection to an A.C. voltage by means of terminals 10 and 11, the series-connected impedances comprise two mutually opposed rectifiers 12 and 13. Otherwise, the arrangement is the same as that of FIG. 1.

When the voltage source is connected in the FIG. 2 arrangement, there passes, before the relay 6 has been energized and during the positive half-periods of the AC. voltage present at the terminal 11, a current through the rectifier 13, the relay winding and the lamp 3. A current continues to flow through the circuit comprising the lamp 3 and the rectifier 12 even during the negative halfperiods owing to the magnetic energy stored in the relay 6. The relay, therefore, receives a direct current and is energized to connect the lamp 3 to the switch 4. If the switch 4 is then non-conductive, no change in the current distribution takes place. However, if the switch is closed, the second half-period of the A.C. voltage is rectified by the rectifier 12 and the current resulting from the stored-up magnetic energy passes through the rectifier 13. Therefore, the relay 6 is fed constantly with direct current as long as the lamp 3 is in order, irrespective of the position of the switch 4.

If an interruption occurs in the lamp 3 when the switch 4 is conductive, the condition of the relay 6 does not change, since a current continues to flow through the rectifier 12, the relay winding and the switch 4. However, when the switch 4 becomes non-conductive in response to the control member 5, at which time the rectifier 13 should enter into operation, no current can flow through it and through the relay winding owing to the interruption in the lamp 3. Consequently, the relay 6 is deenergized and connects the stand-by lamp in circuit through its break-contact. At the same time, the connection between the switch 4 and the rectifier 12 is broken, causing the relay 6 to remain deenergized upon the subsequent closing of the switch 4, whereby the relay remains deenergized and the stand-by lamp inserted in the circuit so as to receive current through the switch 4.

The FIG. 3 arrangement has no periodically controlled switch and can be used in case a fixed light from the lamp is desired. The contacts 10 and 11 are assumed to be connected to an A.C. source. The normally operative lamp 3 is now in series with the winding of a current relay 14, the make-contact of which is in series with the rectifier 12. The operating winding of the relay 6 is now in parallel with a rectifier 15. The operation of the arrangement is the same as that of the preceding circuit with the difference that the rectifier 15 has been added to take up the current flowing from the magnetic energy stored in the relay 6 before the relay 6 and with it the relay 14 has been energized. A possible failure of the normally operative lamp 3 will in this case cause the energization of the current relay 14, which in turn results in deenergization of the relay 6 and insertion of the stand-by lamp 7.

In the FIG. 4 arrangement, the series-connected impedances are formed by the primaries of two transformers 16 and 17. The primary of the transformer 16 is then in parallel with the normally operative lamp 3, whereas that of the transformer 17 is in parallel with the switch 4. The secondaries of the two transformers are in series with each other and with the operative winding of the relay 6. When this arrangement is connected to the current source, the current flowing through the transformer 17 causes energization of the relay 6 and insertion snare/'4.

of the ordinary lamp 3 in the circuit. The relay is then held energized by the current flowing through the transformer 17 as long as the switch 4 is non-conductive and by the current passing through the transformer 16 when the switch t is conductive. A failure of the normally operative lamp 3 makes the transformers simultaneously operative upon the interruption in the switch 4, but since the arrangement is chosen in such a way that the currents flowing through the secondaries counteract each other in the operating winding of the relay 6, the result is that this relay is deenergized and inserts the stand-by lamp 7 in the circuit. This lamp remains connected in the circuit until the normally operative lamp 3 has been replaced. The FIG. 4 arrangement is of advantage in that the operative winding of the relay 6 can be proportioned for a low voltage owing to the presence of the transformers l6 and 117.

The basic circuit arrangement of FIG. 1 may be utilized to cause the successive connection of a plurality of stand-by lamps as these break down one after the other. An arrangement of this type, based on the circuit arrangement of FIG. 4, for connecting an arbitrary number of stand-by lamps after each other is shown in FIG. 5. In this circuit, the relay 6 is provided with an additional break-contact inserted in the connection from the terminal 11 to the primary of a transformer 18, which corresponds to the transformer 17. The stand-by lamp 7 is in parallel with the primary of a transformer 19, which corresponds to the transformer .16 of the preceding stage. The secondaries of the two transformers l8 and 19 feed the operative winding of a relay 2%, which corresponds to the relay 6. The arrangement may comprise further units corresponding to the unit 21, which contains a standby lamp, two transformers and a relay, so that it is possible to have a arbitrary number of stand-by lamps in the arrangement. The circuit arrangement of the last stand by lamps in the series 22 and 23 is then in complete accordance with the FIG. 4 circuit. :From the foregoing description, it is clear that when the FIG. circuit is connected for operation, the normally operative lamp 3 is first connected to the switch 4 and operates until a failure occurs in this lamp. This causes the insertion of the stand-by lamp 7, and upon a possible failure of this lamp the other stand-by lamps of the arrangement are inserted one after the other.

If the arrangement of the invention is placed for instance in a beacon which is controlled from a distant command post, the relay 6, the relay 20, etc., may have i additional contacts for operating suitable signal members at the command post to indicate when the stand-by lamps have been connected in circuit. When failing lamps are replaced, the arrangement returns automatically to the normal operating condition.

What is claimed is:

1. An electrical circuit comprising terminals for connection to a source of current, a load, a flasher contact connected in series with said terminals and load, means for intermittently closing and opening said flasher contact, a relay comprising a winding and a make and break contact, first impedance means connected in parallel with said load through said winding, second impedance means connected in parallel with said flasher contact through said winding, said make and break contact being in series with said flasher contact and said load with the winding connected intermediate said load and said make and break contact, and a second load in parallel with said first load series connected to said make and break contact and said terminals.

2. An electrical circuit arrangement as claimed in claim 1, in which said two impedances comprise a pair of oppositely connected rectifiers.

3. An electrical circuit arrangement as claimed in claim 1, in which said two impedances are the primary windings of two transformers, said relay winding being series-connected with the mutually series-connected secondary windings of said transformers.

4. An electical circuit comprising terminals for connection to a source or current, a load, a first relay winding and a second relay make and break contact in series with said load, a make and break contact of said first relay in parallel with said load and first relay winding, a rectifier in series with said first relay contact, a second relay winding and a second rectifier in series with each other, and in parallel with the contact of said second relay, a third rectifier in parallel with said windings, and a second load in parallel with said first load series connected to said second relay contact and said terminals.

References Cited by the Examiner UNlTED STATES PATENTS "2,197,700 4/40 MacGregor "340-451 DAVID J. GALVIN, Primary Examiner. ARTHUR GAUSS, JAMES D. KALLAM, Examiners. 

1. AN ELECTRICAL CIRCUIT COMPRISING TERMINALS FOR CONNECTIN TO A SOURCE OF CURRENT, A LOAD, A FLASHER CONTACT CONNECTED IN SERIES WITH SAID TERMINALS AND LOAD, MEANS FOR INTERMITTENTLY CLOSING AND OPENING SAID FLASHER CONTACT, A RELAY COMPRISING A WINDING AND A MAKE AND BREAK CONTACT, FIRST IMPEDANCE MEANS CONNECTED IN PARALLEL WITH SAID LOAD THROUGH SAID WINDING, A SECOND IMPEDANCE MEANS CONNECTED IN PARALLEL WITH SAID FLASHER CONTACT THROUGH SAID WINDING, SAID MAKE AND BREAK CONTACT BEING IN SERIES WITH SAID FLASHER CONTACT AND SAID LOAD WITH THE WINDING CONNECTED INTERMEDIATE SAID LOAD AND SAID MAKE AND BREAK CONTACT, AND A SECOND LOAD IN PARALLEL WITH SAID FIRST LOAD SERIES CONNECTED TO SAID MAKE AND BREAK CONTACT AND SAID TERMINALS. 